The present invention relates to electronic camera shutter control circuits and more particularly to a new and improved electronic camera shutter control circuit having an indicator for indicating when the camera shutter is open.
Electronic camera shutter control circuits of various types are known. In one type of known control circuit an output transistor is alternatively connected to an electronic display device or an electromagnet through a change-over switch. This structure enables the control circuit for both an indicating function for indicating the brightness of the scene to be photographed and for controlling the exposure time by controlling the energization of the electromagnet. However, the reliability of this circuit is dependent upon the reliability of the change-over switch and it is difficult and expensive to realize a highly reliable change-over switch within the small space of a camera shutter.
In another of the known types of shutter control circuits a lamp or other indicating device is connected in parallel with an electromagnet energized under control of the control circuit. Consequently, when the electromagnet is energized the lamp will also be energized and indicate that the camera shutter is open. In this way, the control circuit may also be used for detecting the brightness of the scene to be photographed before exposure of the film. However, the parallel arrangement of the lamp and electromagnet results in high operating currents and hence short battery life.